It is known that, when a control movement has to be transmitted, with a given force, between mechanical elements which are separated or apart from one another, a flexible cable is used which allows the precise transmission of movements and of control forces, even in sinuous routes.
Utilization of remote control cables for the transmission of data and forces are frequently found in the mechanical industry. For example, in the automotive industry, cables are traditionally used to transmit forces between elements which are spaced from one another, such as in an engine, the control forces of an accelerator pedal and a clutch pedal and to transmit the control forces of a gear lever to a gear box.
A transmission cable which allows the transmission of reciprocal movements in two directions (i.e., push-pull type) comprises a flexible internal cable which allows for the transmission of tension and compression forces, and a flexible outside shield or sheath in which the cable slides with minimum play. The constant linear dimension of the two elements along the axis of the cable determine the precision of the transmission of movement of the cable.
Normally terminals are provided at the two ends of the internal cable, the terminal permits for an articulated connection to a movement transmitter and to a movement receiver element meanwhile, the two ends of the flexible outside cover have means to thereby fix a respective end of the flexible outside cover to the supports of the respective element.
Due to the structure and under the action of stresses and the wear of the materials caused by variation of temperature. In use, the inner cable and the outer sheath are subject to small plastic deformations caused by the stress acting on the ends of the cable and the wear of the material caused by temperature variations, which change the length of the elements. In addition, the relative distance between the mechanical elements interconnected by the transmission cable is subject to changes in tolerances of the whole set of components and of the supports existing between the elements, which may not be previously and precisely determined.
The effects of the above mentioned factors create the need of a system which allows the regulation of the cable length upon the assembly and during the whole useful life thereof, in order to compensate the variations of length during the use.
For such purposes, transmission cables having an adjustment system to adjust the length thereof are used. The adjustment system comprises a male and female thread system, with tightening lock nuts located in the terminal ends of the cable. The regulation is made by loosening the thread at the terminal of the cable, fixing the position of the cable and then tightening the lock nut.
A male/female threaded adjustment system is difficult to use because access to the system is frequently difficult. The adjustment of the nut, especially the tightening of the lock nut in a male/female threaded adjustment system typically, requires the use of two tools, and the access of the operator hands is limited within the existing space, which makes such adjustment quite complex, time consuming and imprecise.
In addition, safe operation of the vehicle is difficult to achieve since it is uncertain whether the lock nut has been tightly screwed on.